The present invention relates to a vehicle braking device.
In addition, the present invention relates to an improved vehicle braking system wherein output ports of a master cylinder operated by an operator are connected to one of a front wheel brake and a rear wheel brake and to a pressure intensification mechanism for generating a hydraulic pressure intensified in response to a hydraulic pressure outputted from the output port of the master cylinder, whereby the other of the front wheel brake and the rear wheel brake is operated by virtue of the hydraulic pressure generated from the pressure intensification mechanism.
Further, the present invention also relates a braking system for automotive two-wheeled vehicles, and in particular to a braking system for automotive two-wheeled vehicles in which a primary wheel cylinder and a secondary wheel cylinder are provided on a wheel brake means for braking a wheel which are adapted to cause the wheel the brake means to operate when supplied with hydraulic pressure, respectively.
The vehicle braking system is disclosed, for example, in a Japanese Patent Unexamined Publication No. Hei. 5-50972 and is already known.
In the vehicle braking system disclosed therein, the pressure intensification mechanism is constituted by a secondary master cylinder operated by a reaction torque when a front wheel brake is operated by a hydraulic pressure outputted from a front wheel master cylinder.
Therefore, functionally, the secondary master cylinder has to be disposed in the vicinity of the wheel and this increases the unsprung load (that is, non-suspended mass) of the vehicle, slightly deteriorating the riding comfort of the vehicle.
In addition, the other braking system for automotive two-wheeled vehicles, is known by for example, Japanese Patent Examined Publication No. Sho. 62-25550. The braking system is constituted in such a manner that first and second disc brakes are disposed on sides of a front wheel, in which an output port of a primary master cylinder for generating a hydraulic pressure when operated by an operator connects to a wheel cylinder of the first disc brake, in which a secondary master cylinder is mounted on a front fork which is adapted to be caused to operate by virtue of a rotational torque which the secondary master cylinder receives from the front wheel in conjunction with the operation of the first disc brake, and in which an output port of this secondary master cylinder connects to a wheel cylinder of a second disc brake. According to this conventional braking system, when the first disc brake is in operation by virtue of a hydraulic pressure outputted from the primary master cylinder, the secondary master cylinder is caused to operate by making use of the rotational torque of the front wheel, and the second disc brake is then caused to operate by virtue of a hydraulic pressure outputted from the secondary master cylinder. Therefore, a great magnitude of braking force can be provided even by applying a relatively small magnitude of operating force to the primary master cylinder, whereby a nimble braking operation can be performed.
In the conventional braking system as described above, since the secondary master cylinder adapted to operate by virtue of the rotational torque of the wheel has to be disposed in the vicinity of the wheel from the functional point of view, the secondary master cylinder increases the unsprung load of an automotive two-wheeled vehicle, and this somehow functions to deteriorate the riding comfort of the vehicle.
The present invention was made in view of the above situations.
It is an object of the present invention to provide an improved vehicle braking system in which a sufficient magnitude of braking force can be provided without increasing the unsprung load of the vehicle.
In addition, it is an object of a first aspect of the present invention to provide a vehicle braking system comprising a proportional pressure intensification valve for generating a boosting hydraulic pressure intensified in proportion to a hydraulic pressure outputted from a master cylinder without increasing the unsprung load of the vehicle.
The object can be achieved by a vehicle braking system, according to the present invention, comprising:
a front wheel brake;
a rear wheel brake;
a master cylinder adapted to be operated by an operator, the master cylinder having output ports of the master cylinder which are connected to one of the front wheel brake and the rear wheel brake;
a hydraulic pressure source; and
a proportional pressure intensification valve for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the master cylinder from the hydraulic pressure source into a hydraulic pressure boosting chamber thereof,
wherein the hydraulic pressure boosting chamber of the proportional pressure intensification valve is connected to the other of the front wheel brake and the rear wheel brake.
In addition, the object can be achieved by a braking system for automotive two-wheeled vehicle, according to the present invention, comprising:
a wheel brake mechanism for braking a wheel, the wheel brake mechanism having a primary wheel cylinder and a secondary wheel cylinder and are adapted to cause the wheel brake mechanism operate when the primary and secondary wheel cylinders are supplied with hydraulic pressure, respectively;
a master cylinder adapted to be operated by an operator, the master cylinder having an output port which connects to the primary wheel cylinder;
a hydraulic pressure source including a hydraulic pump; and
a proportional pressure intensification valve for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the master cylinder from the hydraulic pressure source into a hydraulic pressure boosting chamber thereof, the hydraulic pressure boosting chamber being connected to the secondary wheel cylinder.
Further, it is also an object of a second aspect of the present invention to provide a braking system for automotive two-wheeled vehicle which is constructed so as to braking a wheel of the vehicle in a nimble fashion without increasing the unsprung load thereof.
The aforesaid object, in particularly the aforesaid object of the first aspect of the present invention can be attained by the first to eight feature explained below according to the present invention.
According to a first feature of the invention, there is provided a vehicle braking system comprising a master cylinder adapted to be operated by an operator, a source of hydraulic pressure and proportional pressure intensification valves for each drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the master cylinder from the source of hydraulic pressure into a hydraulic pressure boosting chamber thereof, wherein output ports of the master cylinder are connected to one of pairs of front wheels and rear wheels and wherein the output chambers of the proportional pressure intensification valves are connected to the other pair of the pairs of front wheels and rear wheels.
According to this first feature of the invention, the hydraulic pressure outputted from the master cylinder is supplied to one of the pairs of front wheel brakes and rear wheel brakes for operating the same when the master cylinder is in operation. In addition, the proportional pressure intensification valves draw the boosting hydraulic pressure intensified in proportion to the hydraulic pressure outputted from the master cylinder from the source of hydraulic pressure into the hydraulic pressure boosting chambers thereof for supplying the boosting hydraulic pressure to the other of the pairs of front wheel brakes and rear wheel brakes for operating the same.
Thus, since the proportional pressure intensification valves are adapted to draw the boosting hydraulic pressures intensified in proportion to the hydraulic pressure outputted from the master cylinder from the source of hydraulic pressure for supplying it to the other wheel brake, these proportional pressure intensification valves and the source of hydraulic pressure can freely be mounted on the vehicle body frame at positions higher than the vehicle suspension springs, and such mounting can suppress the increase in the unsprung load of the vehicle, thereby making it possible to maintain the good riding comfort.
Since almost all of the pressurized fluid delivered by the master cylinder is supplied to the one pair of wheel brakes, the amount of pressurized fluid to be delivered by the master cylinder or the length of the operating stroke of an operating member of the master cylinder can be suppressed to a low level.
On the other hand, even if the other pair of wheel brakes that are operated by virtue of the boosting hydraulic pressure is miniaturized, a sufficient magnitude of braking force can be provided.
According to a second feature of the invention, there is provided a vehicle braking system wherein one of a front wheel brake and a rear wheel brake constitutes a first wheel brake and the other does a second wheel brake, wherein a primary wheel cylinder and a secondary wheel cylinder which are independent from each other are provided on at least the first wheel brake, and wherein output ports of a first master cylinder and a second master cylinder which are individually operated by an operator are connected, respectively, to the primary wheel cylinder of the first wheel brake. and a wheel cylinder of the second wheel brake, and comprising a source of pressurized fluid and a proportional pressure intensification valve for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the first master cylinder into a hydraulic pressure boosting chamber thereof, the hydraulic pressure boosting chamber of the proportional pressure intensification valve being connected to a secondary wheel cylinder of the second wheel brake.
According to this second feature of the invention, in a vehicle such as an automotive two-wheeled vehicle provided with first and second master cylinders for operating a first wheel brake (for example, a front wheel brake) and a second wheel brake (for example, a rear wheel brake), respectively, even when only the first master cylinder is in operation, the hydraulic pressure outputted therefrom operates the first wheel brake and the hydraulic pressure so outputted is also applied to the proportional pressure intensification valve and the boosting hydraulic pressure in proportion to the outputted hydraulic pressure is drawn from the source of hydraulic pressure, by virtue of which the second wheel brake is operated, thus making it possible to operate the first and second brakes in conjunction with each other.
In this case, too, since the proportional pressure intensification valve and the source of pressure can be mounted on the vehicle body frame at positions higher than the suspension springs of the vehicle, such mounting can suppress the increase in the unsprung load of the vehicle, thereby making it possible to maintain the good riding comfort. In addition, since almost all of the pressurized fluid delivered by the first master cylinder is supplied to the first wheel brake, the amount of pressurized fluid so delivered thereby or the length of the operating stroke of the first master cylinder can be maintained small.
Furthermore, according to a third feature of the invention, there is provided a vehicle braking system wherein a primary wheel cylinder and a secondary wheel cylinder which are independent from each other are provided on a front wheel brake, wherein a primary wheel cylinder and a secondary wheel cylinder which are independent from each other are provided on a rear wheel brake, and wherein output ports of a front wheel master cylinder and a rear wheel master cylinder which are individually operated by an operator are connected, respectively, to the primary wheel cylinder of the front wheel brake and the primary wheel cylinder of the rear wheel brake, and comprising a source of pressurized fluid, a first proportional pressure intensification valve for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the front wheel master cylinder from the source of hydraulic pressure into a hydraulic pressure boosting chamber thereof, and a second proportional pressure intensification valve for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the rear wheel master cylinder from the source of hydraulic pressure into a hydraulic pressure boosting chamber thereof, the hydraulic pressure boosting chamber of the first proportional pressure intensification valve being connected to the secondary wheel cylinder of the rear wheel brake and the hydraulic pressure boosting chamber of the second proportional pressure intensification valve being connected to the secondary wheel cylinder of the front wheel brake.
According to this third feature of the invention, a vehicle such as an automotive two-wheeled vehicle provided with a front wheel master cylinder and a rear wheel master cylinder for operating a front wheel brake and a rear wheel brake, respectively, even when only the front wheel master cylinder is in operation, the hydraulic pressure outputted therefrom is supplied to the primary wheel cylinder of the front wheel brake, and the same hydraulic pressure so outputted is also applied to the first proportional pressure intensification valve to thereby draw the boosting hydraulic pressure in proportion to the outputted hydraulic pressure from the source of hydraulic pressure for supply to the secondary wheel cylinder of the rear wheel brake, whereby the front and rear wheel brakes can be operated together.
In addition, even when only the rear wheel master cylinder in operation, the hydraulic pressure outputted therefrom is supplied to the primary wheel cylinder of the rear wheel brake, and the same hydraulic pressure so outputted is also applied to the second proportional pressure intensification valve to thereby draw the boosting hydraulic pressure in proportion to the outputted hydraulic pressure from the source of hydraulic pressure for supply to the secondary wheel cylinder of the front wheel brake, whereby the front and rear wheel brakes can be operated together.
In this case, too, since the first and second proportional pressure intensification valves and the source of hydraulic pressure can freely be mounted on the vehicle body frame at positions higher than the suspension springs of the vehicle, such mounting can suppress the increase in the unsprung load of the vehicle, thereby making it possible to maintain the good riding comfort. In addition, since almost all of the pressurized fluid delivered by the front wheel master cylinder is supplied to the front brake and almost all of the pressurized fluid delivered by the rear wheel master cylinder is supplied to the rear wheel brake, the amounts of the pressurized fluid delivered by the respective master cylinders can be small and therefore, the lengths of the operating strokes of the respective master cylinders can be maintained short.
Furthermore, according to a fourth feature of the invention, there is provided a vehicle braking system wherein first and second proportional pressure intensification valves are constructed such that output characteristics thereof are differentiated from each other.
According to this fourth feature of the invention, the operating characteristics of the front and rear wheel brakes can be differentiated by differentiating the output characteristics of the first and second proportional pressure intensification valves, whereby a braking system can be provided for a vehicle relatively easily which can meet an application thereof.
Moreover, according to a fifth feature of the invention, in addition to the third feature of the invention, there is provided a vehicle braking system, wherein the effective pressure receiving area of the secondary wheel cylinder of the front wheel brake is set smaller than the effective pressure receiving area of the primary wheel cylinder of the rear wheel brake, while the effective pressure receiving area of the secondary wheel cylinder of the rear brake is set smaller than the effective pressure receiving area of the primary wheel cylinder of the front brake, whereby the braking force of the front wheel becomes larger than that of the rear wheel brake when the front wheel master cylinder is in operation, while the braking force of the rear wheel brake becomes larger than that of the front wheel brake when the rear wheel master cylinder is in operation.
According to the fifth feature of the invention, when the front wheel master cylinder is in operation, a state is provided in which the front and rear wheel brakes operate in an interlocking fashion with importance being attached to braking by the front wheel brake, while when the rear wheel master cylinder is in operation, a state is provided in which the front and rear wheel brakes operate in an interlocking fashion with importance being attached to braking by the rear wheel brake, thereby making it possible to obtain a good braking feeling free from a feeling of physical disorder as felt with a non-interlocking braking system for general automotive two-wheeled vehicles.
In addition, according to a sixth feature of the invention, in addition to any of the second to fifth features, there is provided a vehicle braking system wherein the proportional pressure intensification valves are constructed such that the proportional pressure intensification valves start to operate after the hydraulic pressures outputted from the master cylinders corresponding thereto increase to exceed certain levels.
According to this sixth feature of the invention, a delay in operation initiating timing can be provided between the one of the wheel brakes which is operated by virtue of the hydraulic pressure outputted from the master cylinders and the other wheel brake operated by virtue of the boosted hydraulic pressure outputted from the proportional pressure intensification valves.
Furthermore, according to a seventh feature of the invention, in addition to any of the third to fifth features, there is provided a vehicle braking system wherein the second proportional pressure intensification valve is constructed such that the second proportional pressure intensification valve starts to operate after the hydraulic pressure outputted from the rear wheel master cylinder increases to exceed a certain level.
According to this seventh feature of the invention, when the rear wheel master cylinder is in operation, the operation initiating timing of the front wheel brake is delayed from that of the rear wheel brake, whereby jackknifing of the vehicle body can be prevented.
Moreover, according to an eighth feature of the invention, in addition to any of the second to seventh features, there is provided a vehicle braking system wherein an operation stopping means is provided on the source of hydraulic pressure for optionally stopping the operation of the source of hydraulic pressure.
According to this eighth feature of the invention, the functions of the proportional pressure intensification valves can be stopped by stopping the operation of the source of hydraulic pressure by operating the operation stopping means. With this construction, the front and rear wheel brakes can be operated in the general and conventional independent mode as required.
The aforesaid object, in particularly the aforesaid object of the second aspect of the present invention can be attained by the ninth to eleventhh feature explained below according to the present invention.
According to a ninth feature of the invention, there is provided a braking system for automotive two-wheeled vehicles in which a primary wheel cylinder and a secondary wheel cylinder are provided on a wheel brake means for braking a wheel which are adapted to cause the wheel brake means to operate when the primary and secondary wheel cylinders are supplied with hydraulic pressure, respectively, characterized in that
an output port of a master cylinder connects to the primary wheel cylinder, and that a hydraulic pressure boosting chamber of a proportional pressure intensification valve for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the master cylinder from a source of hydraulic pressure including a hydraulic pump connects to the secondary wheel cylinder.
According to this ninth feature of the invention, when the master cylinder is in operation, the output hydraulic pressure outputted therefrom is supplied to the primary wheel cylinder, and the boosted hydraulic pressure outputted in proportion to the output hydraulic pressure from the master cylinder from the proportional pressure intensification valve is supplied to the secondary wheel cylinder, and therefore, the operator only has to apply a relative small magnitude of operation force to the master cylinder to strongly brake the front wheel.
Moreover, the source of hydraulic pressure and the proportional pressure intensification valve which are used to supply the boosted pressure to the wheel brake means can be freely mounted on an upper portion of a front fork or a body frame of the automotive two-wheeled vehicle at positions higher than the suspension springs thereof, and such mounting can help suppress the increase in unsprung load of the automotive two-wheeled vehicle, thereby making it possible to maintain the good riding comfort.
Furthermore, should there occur a failure in the source of hydraulic pressure, thereby making it impossible for the proportional pressure intensification valve to output any pressure, since the output hydraulic pressure outputted from the master cylinder can be supplied to the primary wheel cylinder, the wheel brake means is allowed to operate normally, a fail-safe function being thereby secured.
In addition to the first feature, according to a tenth feature of the invention, there is provided a braking system for automotive two-wheeled vehicles, wherein the wheel brake means comprises a disc brake disposed on at least one side of the wheel and wherein the primary and secondary wheel cylinders are disposed together on a caliper of the disc brake.
According to this tenth feature, the construction of the wheel brake means can be simplified.
In addition to the ninth feature, according to a eleventh feature of the invention, there is provided a braking system, wherein the wheel brake means comprises first and second disc brakes disposed on both sides of the wheel and wherein a wheel cylinder of the first disc brake is made to function as the primary wheel cylinder, while a wheel cylinder of the second disc brake is made to function as the secondary wheel cylinder.
According to this eleventh feature, the braking effect of the wheel can be improved.
Further, the above-mentioned object can be attained by a braking system for vehicle, according to the present invention comprising:
a first brake member (1061, 1062; 541542);
a second brake member (1062, 1061; 542, 541) independent from the first brake member;
a master cylinder (M, Mf, Mr) adapted to be operated by an operator, the master cylinder having output port which is connected to the first brake member;
a hydraulic pressure source (107, S); and
a proportional pressure intensification valve (V, V1, V2) for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the master cylinder (M, Mf, Mr) from the hydraulic pressure source (107, S) into a hydraulic pressure boosting chamber (130, 30) thereof,
wherein the hydraulic pressure boosting chamber of the proportional pressure intensification valve is connected to the second brake member.
In the above-mentioned braking system, it is advantageous that the vehicle comprises front and rear wheel brake mechanisms (B, Bf, Br), at least one of the front and rear wheel brake mechanisms (B, Bf, Br) has a primary wheel cylinder (1061, 541) and a secondary wheel cylinder (1062, 542) which are adapted to cause the at least one when the primary and secondary wheel cylinders (1061, 1062; 541, 542) are supplied with hydraulic pressure, and the first brake member (1061, 541) is the primary wheel cylinder (1061, 541) of the at least one of front and rear wheel brake mechanisms, and the second brake member (1062, 542) is the secondary wheel cylinder (1062, 542) of the at least one of front and rear wheel brake mechanisms.
Further, in the braking system for vehicle according to the present invention, it is further advantageous that the vehicle is an automotive two-wheeled vehicle, the at least one of front and rear wheel brake mechanisms (B, Bf) comprises a disc brake disposed on at least one side of the respective wheel (Wf), and the primary and secondary wheel cylinders (1061, 1062) are disposed together on a caliper (104) of the disc brake.
In addition, the braking system for vehicle according to the present invention, it is preferable that the vehicle is an automotive two-wheeled vehicle, the at least one of the front rear wheel brake mechanisms (Bf) comprises first and second disc brakes (B1, B2) disposed on both sides of the respective wheel (Wf) and wherein a wheel cylinder of the first disc brake (B1) is made to function as the primary wheel cylinder (1061), while a wheel cylinder of the second disc brake (B2) is made to function as the secondary wheel cylinder (1062).
Further, in the above-mentioned braking system for vehicle according to the present invention, it is preferred that the vehicle comprises front and rear wheel brake mechanisms (Bf, Br), each of the front and rear wheel brake mechanisms (Bf, Br) has a wheel cylinder (541, 542) which is adapted to cause the respective wheel brake mechanism, the first brake member is the wheel cylinder (541) of one of the front and rear wheel brake mechanisms (Bf), and the second brake member is the wheel cylinder (542) of the other of the front and rear wheel brake mechanisms (Br).
Furthermore, in the braking system for vehicle according to the present invention, it is advantageous that the vehicle comprises front and rear wheel brake mechanisms (Bf, Br), each of the front and rear wheel brake mechanisms has a primary wheel cylinder (541) and a secondary wheel cylinder (542) which are adapted to cause the respective wheel brake mechanism, and the first brake member is the primary wheel cylinder (541) of one of the front and rear wheel brake mechanisms (Bf), and the second brake member is the secondary wheel cylinder (542)of the other of the front and rear wheel brake mechanisms (Br).
Moreover, in the above-mentioned construction of the vehicle braking system, it is more advantageous that the master cylinder (M) comprises a front wheel master cylinder (Mf) with output port (551) connected to the primary wheel cylinder (541) of the front wheel brake (Bf), and also a rear wheel master cylinder (Mr) with output port (552) connected to the primary wheel cylinder (541) of the rear wheel brake (Br), the front and wheel master cylinders (Mf, Mr) being independently operated by the operator, and
the pressure intensificaiton valve (V1, V2) comprises
a first proportional pressure intensification valve (V1) for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the front wheel master cylinder (Mf) from the source of hydraulic pressure (S) into a hydraulic pressure boosting chamber (30) thereof, and
a second proportional pressure intensification valve (V2) for drawing a boosting hydraulic pressure in proportion to a hydraulic pressure outputted from the rear wheel master cylinder (Mr) from the source of hydraulic pressure (S) into a hydraulic pressure boosting chamber (30) thereof,
wherein the hydraulic pressure boosting chamber (30) of the first proportional pressure intensification valve (V1) is connected to the secondary wheel cylinder (542) of the rear wheel brake (Br), and the hydraulic pressure boosting chamber (30) of the second proportional pressure intensification valve (V2) is connected to the secondary wheel cylinder (542) of the front wheel brake (Bf).
Further, in the vehicle braking system according to the present invention, it is preferred that the first and second proportional pressure intensification valves (V1, V2) are different in its output characteristic from each other.
Furthermore, in the vehicle braking system according to the present invention, it is advantageous that the effective pressure receiving area of the secondary wheel cylinder (542) of the front wheel brake (Bf) is set smaller than the effective pressure receiving area of the primary wheel cylinder (541) of the rear wheel brake (Br), while the effective pressure receiving area of the secondary wheel cylinder (542) of the rear wheel brake (Br) is set smaller than the effective pressure receiving area of the primary wheel cylinder (541) of the front wheel brake (Bf).
Moreover, in the vehicle braking system, the proportional pressure intensification valve (V1, V2) maybe constructed such that the proportional pressure intensification valve (V1, V2) starts to operate after the hydraulic pressures outputted from the master cylinder (Mf, Mr) is reached to a predetermined value or more.
In addition, in the vehicle braking system according to the present invention, the second proportional pressure intensification valve (V2) may be constructed such that the second proportional pressure intensification valve starts to operate after the hydraulic pressure outputted from the rear wheel master cylinder (Mr) is reached to a predetermined value or more.
Further, in the vehicle braking system, an operation stopping mechanism (60) may be provided on the hydraulic pressure source (S) for optionally stopping the operation of the source of hydraulic pressure (S).